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package cli
import (
"flag"
"strings"
)
type iterativeParser interface {
newFlagSet() (*flag.FlagSet, error)
useShortOptionHandling() bool
}
// To enable short-option handling (e.g., "-it" vs "-i -t") we have to
// iteratively catch parsing errors. This way we achieve LR parsing without
// transforming any arguments. Otherwise, there is no way we can discriminate
// combined short options from common arguments that should be left untouched.
// Pass `shellComplete` to continue parsing options on failure during shell
// completion when, the user-supplied options may be incomplete.
func parseIter(set *flag.FlagSet, ip iterativeParser, args []string, shellComplete bool) error {
for {
err := set.Parse(args)
if !ip.useShortOptionHandling() || err == nil {
if shellComplete {
return nil
}
return err
}
trimmed, trimErr := flagFromError(err)
if trimErr != nil {
return err
}
// regenerate the initial args with the split short opts
argsWereSplit := false
for i, arg := range args {
// skip args that are not part of the error message
if name := strings.TrimLeft(arg, "-"); name != trimmed {
continue
}
// if we can't split, the error was accurate
shortOpts := splitShortOptions(set, arg)
if len(shortOpts) == 1 {
return err
}
// swap current argument with the split version
// do not include args that parsed correctly so far as it would
// trigger Value.Set() on those args and would result in
// duplicates for slice type flags
args = append(shortOpts, args[i+1:]...)
argsWereSplit = true
break
}
// This should be an impossible to reach code path, but in case the arg
// splitting failed to happen, this will prevent infinite loops
if !argsWereSplit {
return err
}
}
}
const providedButNotDefinedErrMsg = "flag provided but not defined: -"
// flagFromError tries to parse a provided flag from an error message. If the
// parsing fials, it returns the input error and an empty string
func flagFromError(err error) (string, error) {
errStr := err.Error()
trimmed := strings.TrimPrefix(errStr, providedButNotDefinedErrMsg)
if errStr == trimmed {
return "", err
}
return trimmed, nil
}
func splitShortOptions(set *flag.FlagSet, arg string) []string {
shortFlagsExist := func(s string) bool {
for _, c := range s[1:] {
if f := set.Lookup(string(c)); f == nil {
return false
}
}
return true
}
if !isSplittable(arg) || !shortFlagsExist(arg) {
return []string{arg}
}
separated := make([]string, 0, len(arg)-1)
for _, flagChar := range arg[1:] {
separated = append(separated, "-"+string(flagChar))
}
return separated
}
func isSplittable(flagArg string) bool {
return strings.HasPrefix(flagArg, "-") && !strings.HasPrefix(flagArg, "--") && len(flagArg) > 2
}
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